98' electric cooling fan won't shut off

[Deanh]

Help!
I have a 98 4.0L with a electric cooling fan that will not shut off.

It comes on within 3-5 minutes of starting the Jeep, before it is even fully warmed up.

Once it comes on it will not shut off, even with the ignition turned off. I have to pull the fuse or relay to get it to shut off.

The manual says the relay or coolant temperature switch is faulty. Where is the coolant temperature switch located? How do I test each of these parts?

Could it be something else causing this?

Thanks a lot!

[XJNick]

Hi,

To my knowledge the coolant temperature switch can ONLY activate the fan if the ignition switch is in RUN.

So it is most likely a bad fan relay. They can become bad and stick internally. The only fix is to replace the relay, or tap it against something to release it if it gets stuck (temporary fix)

-Nick

[Deanh]

I replaced the fan relay with a new one and still have the problem.

I'm thinking the coolant temperature switch is faulty and telling the fan to always be on, or whatever tells the fan to turn off is not working. However I think the fan is coming on sooner than needed so my prime suspect is the coolant temp. switch.

The Haynes manual I have is not clear on the switch location, can anyone point me towards it?

[XJNick]

That strikes me as odd... I know that pre '97 XJs elec. fans cannot come on through the temp. sensor unless the ignition switch in RUN.

So, either the wiring was altered during the '97+ model year revisions to the cherokee, OR you have a bad Auto Shut Down relay (ASD), or maybe a short somewhere.

The temp sensor for the fan used to be located on the driver's side of the radiator (screwed into the back of the radiator). Your could be somewhere else.

-Nick

[Deanh]

Found the problem.

The connectors for the rely were corroded and shorting it out.

Cleaned them up and problem solved.

[XJNick]

Interesting. Glad to hear you found the problem

-Nick